High Voltage Positive Electrode Active Material Including Lithium Manganese-Based Oxide and Method for Producing the Same

Abstract

A positive electrode active material contains a lithium-rich lithium manganese-based oxide, wherein the lithium manganese-based oxide has a composition of the following chemical formula (1), and wherein a lithium ion conductive glass-ceramic solid electrolyte layer containing at least one selected from the group consisting of thio-LISICON(thio-lithium super ionic conductor), LISICON(lithium super ionic conductor), Li2S—SiS2—Li4SiO4, and Li2S—SiS2—P2S5—Lil is formed on the surface of the lithium manganese-based oxide particle:Li1−xMyMn1−x−yO2−zQz   (1)wherein, 0<x≤0.2, 0<y≤0.2, and 0≤z≤0.5;M is at least one element selected from the group consisting of Al, Mg, Ni, Co, Fe, Cr, V, Ti, Cu, B, Ca, Ga, In, Ru, Zn, Zr, Nb, Sn, Mo, Sr, Sb, W, Ti and Bi; andQ is at least one element selected from the group consisting of P, N, F, S and Cl.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)[0001]This application claims the benefit of filing dates of Korean Patent Application No. 10-2017-0124381 filed with Korean Intellectual Property Office on Sep. 26, 2017, and Korean Patent Application No. 10-2018-0091426 filed with Korean Intellectual Property Office on Aug. 6, 2018 the entire contents of which are incorporated herein by reference.TECHNICAL FIELD[0002]The present invention relates to a high voltage positive electrode active material including a lithium manganese-based oxide and a method for producing the same.BACKGROUND ART[0003]In accordance with technological development and increased demand for mobile devices, demand for using secondary batteries as energy sources has rapidly increased. Among these secondary batteries, lithium secondary batteries having high energy density and operating potential, long cycle life, and low self-discharge ratio are commercially available and widely used.[0004]Also, in line with growing conc...

AI Technical Summary

Benefits of technology

The present inventors found that using a positive electrode active material with a specific solid electrolyte layer on the surface of lithium-rich lithium manganese-based oxide particles can improve the performance of battery cells. SiO2 or SiS2 components in the solid electrolyte layer can enhance surface stability and conductivity, although high levels of SiO2 or SiS2 can reduce ion conductivity. The maximum content of SiO2 or SiS2 is preferably 10%.

Problems solved by technology

Among the above-mentioned positive electrode active materials, LiCoO2 is most commonly used due to its excellent lifetime characteristics and high charge-discharge efficiency, but has low structural stability.

In addition, due to the resource limitations of cobalt, which is a raw material, LiCoO2 is expensive, and therefore price competitiveness is low, whereby the massive use thereof as power sources in fields such as electric vehicles is limited.

In addition, lithium manganese oxides such as LiMnO2, LiMn2O4, etc. have merits of excellent thermal safety and low price but entail disadvantages such as low capacity, poor cycle life characteristics, poor high-temperature characteristics, etc.

However, the oxide containing excessive lithium has a high irreversible capacity.

Furthermore, in addition to lithium, oxygen escapes from the active material structure at the time of high-voltage activation to utilize excessive lithium.

As a result, it has been found that the active material structure may collapse, a voltage sagging phenomenon resulting therefrom may occur, the deterioration of the battery cell may be accelerated, an increase of the resistance and generation of gas and the like may be caused due to decomposition of the electrolyte according to high-voltage driving, thereby further accelerating deterioration of the battery cell.

However, the above-mentioned techniques have limitations in continuously raising the operating voltage for ever-increasing need.

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